Linear Regression
Item 1
If there are 6 petals on a flower, how much will an elephant plant weigh (in pounds):
Petals Weight
8 1
5 6
2 7
1 8
9 2
SSx = _____
SSy = _____
SSxy = ____
a = _____
b = _____
Item 2
If there are 9 dolls, how many truckes will a child have:
Trucks Dolls
12 11
8 7
6 5
2 1
4 3
9 9
14 15
a = _____
b = _____
r = _____
standard error of estimate (SEE) = _____
Item 3
If your high school GPA is 3.3, what would you predict your college GPA to be:
High Schl College
1.0 3.9
2.5 3.7
3.3 1.4
4.0 1.0
2.3 2.9
a = _____
b = _____
Item 4
If there are 22 ducks, how many cows will the farmer own:
Ducks Cows
3 11
6 6
9 8
11 1
15 2
4 10
5 7
a = _____
b = _____
r = _____
standard error of estimate (SEE) = _____
Item 5
If there are 3 doctors, how many nurses will a hospital have
9 15
4 5
2 3
11 1
16 18
17 10
a = _____
b = _____
see = _____
Item 6
If there are 7 professors, how many classes will be taught:
Professors Classes
1 3
4 8
12 13
8 2
7 8
7 9
a =
b =
r =
see =
If X (professors) is 7, Y (classes) will be =<
Item 7
If there are 150 candles, how many flowers will a wedding have?
Candles Flowers
22 2
8 4
6 9
3 11
12 4
1 6
16 19
a =
b =
How accurate is your prediction? (see) =
If X is 150 (candles), Y (flowers) will be
Item 8
How much will tuition (in thousands) be in 1997:
Year Tuition
1990 1
1991 3
1992 9
1993 12
1994 16
a =
b =
[Hint: use the last digit of the year or convert Years to your own integers]
If X (year) is 7, Y (tuition) will be =
ANSWERS
Item 1
If there are 6 petals on a flower, how much will an elephant plant weigh (in pounds):
Petals Weight
8 1
5 6
2 7
1 8
9 2
SSx = 50
SSy = 38.8
SSxy = – 42
a = 9
b = – .84
with an r of – .95, this is a strong correlation and a good predictor
6 pearls predict s 3.86 pounds
Item 2
If there are 9 dolls, how many truckes will a child have:
Trucks Dolls
12 11
8 7
6 5
2 1
4 3
9 9
14 15
Dolls are predicting Trucks
a =. 1.47
b = .88
r = .99
standard error of estimate (SEE) = .57
9 dolls predicts 9.36 trucks
Item 3
If your high school GPA is 3.3, what would you predict your college GPA to be:
High Schl College
1.0 3.9
2.5 3.7
3.3 1.4
4.0 1.0
2.3 2.9
a = 5.33
b = – 1.05
r = – .90
standard error of estimate (SEE) = .68
High school grades are not a predictor of college grades
3.3 predicts 1.87
Item 4
If there are 22 ducks, how many cows will the farmer own:
Ducks Cows
3 11
6 6
9 8
11 1
15 2
4 10
5 7
a = 8.17
b = – .17
r = – .17
standard error of estimate (SEE) = 4.89
22 ducks predicts 4.35 cows
Item 5
If there are 3 doctors, how many nurses will a hospital have
Doctors Nurses
9 15
4 5
2 3
11 1
16 18
17 10
a = 2.42
b = .63
see = 6.28
With an r of .57, not going to predict we’ll.
3 doctors predicts 4.33 nurses
Item 6
If there are 7 professors, how many classes will be taught:
Professors Classes
1 3
4 8
12 13
8 2
7 8
7 9
a = 2.82
b = .67
r = .61
see = 3.60
If X (professors) is 7, Y (classes) will be = 7.5
Item 7
If there are 150 candles, how many flowers will a wedding have:
Candles Flowers
22 2
8 4
6 9
3 11
12 4
1 6
16 19a = 8.24
b = – .04
How accurate is your prediction? (see) = 6.36
If X is 150 (candles), Y (flowers) will be = 2.27
Item 8
How much will tuition (in thousands) be in 1997:
Year Tuition
1990 1
1991 3
1992 9
1993 12
1994 16
a = .40
b = 3.90
Hint: use the last digit of the year or convert Years to your own integers
If X (year) is 7, Y (tuition) will be = 27.7
